> If I could develop my application strictly in C, my problems accessing > LittleCMS would be non-existent, > but I need to develop in C# :(
Working with C# is not too bad! >[...] > cmsDoTransform(cmsHTRANSFORM Transform, const void * InputBuffer, > void * OutputBuffer, > cmsUInt32Number Size); > > (Not sure what the 'const' keyword in front of the first void * statement > does?) By writing 'const' Marti is telling us, that cmsDoTransform will not touch the data in InputBuffer. I.e. we can either pass a const void* or we can pass a void*. If he would had omit to write 'const' and we would have just a const void* inputBuffer we could not pass this pointer to cmsDoTransform (compiler error)... (s. http://stackoverflow.com/questions/4064286/c-const-keyword-explanation) > [DllImport(lcms2Path, CallingConvention = CallingConvention.Winapi)] > static extern void cmsDoTransform(IntPtr xform, IntPtr inputColors [in], > IntPtr outputColors [out], uint Size); > > So my question becomes how do I pass pointers to the these buffers in my new > declaration? > I read somewhere about the need to use the keyword 'unsafe' but I am not > sure. > Also read about the need to use the attributes [in] and [out] in marshalling > the data. > (The Marshalling of data is a HUGE topic in itself as I found out through my > hours of reading online) > > Ultimately, my goal is is to convert JPEG or TIFF images from one color > space to another through LittleCMS. It's not that difficult... Here is what I'm using (somehow stripped, without error handling, without cleanup...) public static class NativeMethods { [DllImport("lcms2.dll")] public static extern void cmsDoTransform( [In] IntPtr Transform, [In] byte[] InputBuffer, [Out] byte[] OutputBuffer, [In] UInt32 Size); } // We use WPF classes to read binary data of the images: // Namespace: System.Windows.Media.Imaging // Assembly: PresentationCore (in PresentationCore.dll) BitmapDecoder biDec = BitmapDecoder.Create(.....) BitmapFrame biFrm = biDec.Frames[0]; PixelFormat inputFormat = biFrm.Format; uint lcmsInputFormat = 0; FormatConvertedBitmap fcb = null; // if we have an input format that we cannot use direktly in lcms // we have to create a temporary bitmap with lcms compatible format and use this instead of biFrm if (inputFormat == PixelFormats.Bgra32) { lcmsInputFormat = 0x44499; // Lcms.Format.TYPE_BGRA_8; } else if (inputFormat == PixelFormats.Bgr24) { lcmsInputFormat = 0x40419; // Lcms.Format.TYPE_BGR_8; } else { inputFormat = PixelFormats.Bgra32; // we enforce Bgra32 format lcmsInputFormat = 0x44499; // Lcms.Format.TYPE_BGRA_8; fcb = new FormatConvertedBitmap(biFrm, inputFormat, null, 0); if (fcb == null) { throw new Exception("Unable to create FormatConvertedBitmap"); } } // create lcms inputprofile IntPtr inputProfileH = IntPtr.Zero; if (biFrm.ColorContexts != null) { byte[] inputProfile = StreamToArray(biFrm.ColorContexts[0].OpenProfileStream()); inputProfileH = Basic.Lcms.NativeMethods.cmsOpenProfileFromMem(inputProfile, (uint)inputProfile.Length); } else { inputProfileH = Basic.Lcms.NativeMethods.cmsCreate_sRGBProfile(); } IntPtr outputProfileH = .....; // create your lcms output profile IntPtr lcmsTrafo = NativeMethods.cmsCreateTransform( inputProfileH , lcmsInputFormat , outputProfileH , lcmsInputFormat // output format = input format , YourRenderingIntent , 0); // copy image data to byte[] int stride = biFrm.PixelWidth * inputFormat.BitsPerPixel / 8; Byte[] inputBitmapData = new Byte[stride * biFrm.PixelHeight]; if (fcb == null) { // we copy pixel data from original image biFrm.CopyPixels(inputBitmapData, stride, 0); } else { // we copy pixel data from format converted bitmap fcb.CopyPixels(inputBitmapData, stride, 0); } // I have to copy the whole data, to get a copy of alpha channel (lcms 2.7) Byte[] outputBitmapData = inputBitmapData.Clone() as Byte[]; NativeMethods.cmsDoTransform(lcmsTrafo, inputBitmapData, outputBitmapData, (uint)(biFrm.PixelWidth * biFrm.PixelHeight)); // create a new image, based on outputBitmapData: BitmapSource ccb = BitmapSource.Create( biFrm.PixelWidth, biFrm.PixelHeight , biFrm.DpiX, biFrm.DpiY , inputFormat , null , outputBitmapData , stride); // create e.g. .png file: BitmapEncoder biEnc = new PngBitmapEncoder(); biEnc.Frames.Add(BitmapFrame.Create(ccb)); biEnc.Save(YourOutputStream); -- lakeBits Inh. Edgar Loser Haydnstr. 25 78464 Konstanz Tel 0049 7531 5844154 0 Fax 0049 7531 5844154 9 http://www.colymp.com/ mailto:lo...@colymp.com ------------------------------------------------------------------------------ Attend Shape: An AT&T Tech Expo July 15-16. Meet us at AT&T Park in San Francisco, CA to explore cutting-edge tech and listen to tech luminaries present their vision of the future. This family event has something for everyone, including kids. Get more information and register today. http://sdm.link/attshape _______________________________________________ Lcms-user mailing list Lcms-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lcms-user
